A sextuply charged cyclic cationic receptor with an extraordinary structure and unprecedented binding properties is presented. The macrocycle consists of six pyridinium ions connected by methylene linkers with an electron-deficient cavity inside. In the solid state, the cavity is padded with an organized water network that gives the macrocycle a hexagonal shape. In water, the cavity is more flexible and selectively accommodates anionic species. Of the ions of similar size the macrocycle binds most strongly those with the largest negative charge. When the net charge is the same, the most preferred are anions with delocalized charge rather that those with localized charge; remarkably, the former form inclusion complexes, while the latter are complexed externally.

中文翻译：

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支柱[6]吡啶鎓：六边形的分子盒，可选择性识别多电荷阴离子物种†

提出了具有异常结构和空前的结合特性的六重带电荷的环状阳离子受体。大环由通过亚甲基接头连接的六个吡啶鎓离子组成，内部具有缺电子腔。在固态状态下，空腔中填充有组织的水网，使大环具有六边形的形状。在水中，腔体更具柔韧性，可以选择性地容纳阴离子物质。在大小相似的离子中，大环与负电荷最大的离子结合最牢固。当净电荷相同时，最优选的是带有离域电荷的阴离子，而不是带离域电荷的阴离子；值得注意的是，前者形成了包合物，而后者则在外部形成了络合物。